JPH0638485A - Bistable magnetic actuator - Google Patents

Abstract

PURPOSE: To keep a stable position of an armature without using electric energy by making the actuator in such a structure that by energizing a coil, the magnetic flux density of the armature may be increased at one and decreased at the other end, and thereby the armature may be moved to another stable position and be kept at the stable position even after the coil has been de-energized. CONSTITUTION: Permanent magnets 12, 13 are mounted at both ends of an armature 7 which can slide in the axis direction of a tube-like liner 2 made of brass located inside an outer shell 1 made of such magnetic material as soft steel. When a current pulse is applied to a coil 3, a magnetic flux caused such that the magnetic flux density at one end of the coil adjacent to a gap 14 is increased and may lessen magnetic flux of a permanent magnet 13 which holds the armature to a pole piece 5. Therefore, the armature moves in response to the current pulse, and a magnet 12 becomes abutted against a pole piece 4 and a gap is generated in the axis direction between the magnet 13 and the pole piece 5. In other words, the armature is moved from a first stable position to a second one and is kept at the second stable position without continuously energizing the coil 3.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to bistable magnetic actuators. Bistable magnetic actuators are used in circuit breakers and other devices.

[0002]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic actuator which can hold any of its stable positions without the need for electrical energy.

The present invention is a bistable magnetic actuator in which an armature of magnetic material is provided in a housing of magnetic material such that the armature is axially movable between two stable positions, the end of the housing being poled. The armature is provided with a rod which is axially slidably guided through one or both pole pieces and the housing substantially extends from one pole piece to the other. Of the armature, the axial dimension of the armature is such that one end of the armature abuts or is adjacent to the corresponding pole piece when the actuator is in either stable position. Is set so that an axial gap is formed between the other end of the armature and the other pole piece, and the permanent magnet acts on the armature and the pole piece without energizing the coil. The magnet is held magnetically in one of two stable positions, and energizing the coil with a suitable current pulse increases the magnetic flux density at the end of the armature adjacent the axial gap. Along with the decrease in the magnetic flux density at the other end of the armature, the armature moves to another stable position and remains stable at that position even after the coil is deenergized. A magnetic actuator is provided.

In one embodiment of the invention, the permanent magnets are axially magnetized magnets attached to the ends of the armature so as to form part of the body of the armature. In this example, the same pole of the magnet faces the pole piece. The armature is slidable inside the brass tubular liner with the air gap between them and a coil is provided between the liner and the housing.

In another embodiment of the invention, the permanent magnets are axially magnetized magnets mounted stationary between the armature and the coil. In this example,
The same magnetic pole of the magnet faces and engages the pole piece. The dimensions of the armature, pole piece and permanent magnet are such that when the armature is in engagement with one pole piece, the plane of extension of the end of the armature that engages that pole piece is between the poles of the associated magnet The penetrating part of the armature is close to the pole piece, but the extension plane at the other end of the armature is set to penetrate between the magnetic poles of the other magnet but far from the other pole piece.

In any of the embodiments, it is advantageous to form the magnet from sintered neodymium.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The bistable magnetic actuator of FIG. 1 is arranged in an outer shell 1 of a magnetic material such as mild steel, a brass tubular liner 2 located therein, and a space between the outer shell 1 and the liner 2. It comprises a magnetic winding 3 (called a coil). The ends of the shell 1 are closed by pole pieces 4 and 5 of a magnetic material such as mild steel, which are fixed to the shell by screws 6.

An armature 7 is provided inside the brass tubular liner 2, and the armature is slidable in the axial direction of the outer shell and the tubular liner. The sliding of the armature 7 is guided by stainless steel rods 8 and 9. These rods are fixed to an armature 7 and slide in brass cylindrical bearing liners 10 and 11 mounted in the center of pole pieces 4 and 5, respectively. There is a small gap between the armature 7 and the brass tubular liner 2.

A permanent magnet 12 is provided at each end of the armature 7.
And 13 are attached. These magnets are magnetized in the axial direction, and are arranged so that the magnetic poles facing away from the main body of the armature 7 have the same pole, for example, the N pole.

The axial length of the armature 7 including the magnets 12 and 13 is such that when one magnet is in contact with one pole piece, for example when the magnet 13 is in contact with the pole piece 5, the other magnet and the other. Is set so that an axial gap 14 is formed between the pole piece and the pole piece. The axial length of the gap 14 determines the stroke when the actuator moves from one stable position to another stable position.

Assuming the actuator is in the position shown in FIG. 1, the actuator retains the position shown without energizing the coil. How firmly it is held in that position depends on the magnetic force existing between the magnet 13 and the pole piece 5. The magnets are preferably made of neodymium, which is able to maintain a very high magnetic flux density in the permanent magnets 12 and 13.

To move the actuator to another stable position, a current pulse may be applied to the coil 3. The duration, magnitude and direction of this current pulse is preferably controlled by an electronic switch to move the armature at a controlled velocity and uniform acceleration.

When a current pulse is applied to the coil 3, a magnetic flux is generated which increases the magnetic flux density of the coil end portion adjacent to the gap 14 and reduces the magnetic flux of the permanent magnet 13 holding the armature on the pole piece 5. To do. Therefore, the armature moves in response to the current pulse, and the magnet 12 causes the pole piece 4 to move.
At the same time as the contact with the pole piece 5, an axial gap is created between the magnet 13 and the pole piece 5. That is, the armature moves from the first stable position to the second stable position and retains its second position without continuing to energize coil 3.

The stainless steel rod 8 is an armature 7
Has the function of transmitting the axial movement of the switch to a switching device, eg a circuit breaker.

The embodiment of FIGS. 2-4 comprises an outer shell 101 of magnetic material such as mild steel and an annular coil 103 therein. Both ends of the outer shell 101 are closed by pole pieces 104 and 105 made of a magnetic material such as mild steel, and these pole pieces are fixed to the outer shell 101 by screws 106.

The armature 107 provided inside the coil is slidable in the axial direction of the outer shell, and the sliding passes through the bearings 110 and 111 of the pole pieces 104 and 105, respectively, and a non-magnetic rod 108 made of, for example, stainless steel. , 109. The armature 107 slides in a brass cylindrical liner 112 coaxial with the coil 103 and the outer shell 101. There is a small air gap of, for example, 1 mm between the armature and the inner wall of the brass cylindrical liner 112.

Coil 103 and brass cylindrical liner 11
The circular disk magnets 113 and 114 are provided between the two. These magnets are axially magnetized and
The poles are arranged to engage the respective pole pieces 104 and 105. These magnets are preferably made of sintered neodymium. When such a magnetic material is used, a very large magnetic force can be obtained with a small amount of material.

Filling material 115 is placed between the south poles of the magnet facing each other.
And brass packing material 116 is provided. The dimensions of the components described above are such that the armature 10 is in contact with the pole piece 104 in one stable position, for example.
Axial gap 1 between 7 and the other pole piece 105
17 is set to exist.

Due to the magnetic action of the magnet on the armature, the armature does not energize the coil 103 but the coil 1
It will remain stable in the position of FIG. 2 until an appropriate current pulse is applied to 03. When a current pulse is applied to the coil 103, a magnetic flux is generated that increases the magnetic flux density at the end of the actuator where the axial gap 177 is located and reduces the magnetic flux of the permanent magnet that holds the armature on the pole piece 104. Therefore, the armature 107 moves to another stable position in response to the current pulse to move the air gap 11
As 7 disappears, another air gap is created between the pole piece 104 and the armature 107.

Although it has been mentioned above that the armature comes into contact with one or the other pole piece, the rod 8, 9 or 10
There may be a small gap between the armature and the pole piece even in the "contact" position due to the limit stop member provided on the link to which 8 and 109 are connected.

The present invention relates to a bistable actuator, which may use any known means for providing a controlled current pulse.

[0023]

[Brief description of drawings]

FIG. 1 is an axial cross-sectional view of a first embodiment of a bistable actuator according to the present invention.

FIG. 2 is an axial cross-sectional view of a second embodiment of a bistable actuator according to the present invention.

3 is a cross-sectional view of the actuator of FIG.

4 is a cross-sectional view taken along the line IV-IV of FIG.

[Explanation of symbols]

 1 outer shell 2 brass tubular liner 3 coil 7 armature 8, 9 stainless steel rod 10, 11 brass cylindrical bearing liner 12, 13 permanent magnet 14 axial gap 101 outer shell 103 annular coil 104, 105 pole piece 107 armature 108 , 109 Non-magnetic rod 110, 111 Bearing 112 Brass cylindrical liner 113, 114 Annular disc magnet

Front Page Continuation (72) Inventor Ralph J. Melfish UK Devon Eight Eight Five Edie Exmouth By Stock Pine Ridge Woodland Lodge (No.)

Claims (9)

[Claims] 1. A bistable magnetic actuator, wherein an armature of magnetic material is provided in a housing of magnetic material for axial movement between two stable positions, the end of the housing being provided by a pole piece. Closed, the armature is provided with a rod which extends axially slidably through one or both pole pieces, the housing being substantially internal to the pole piece from the other pole piece to the other pole piece. It contains a coil that extends to one side of the armature such that one end of the armature abuts a corresponding pole piece or is adjacent to the pole piece and the armature when the actuator is in one of its stable positions. Is set so that an axial gap is formed between the other end of the armature and the other pole piece, and the permanent magnet acts on the armature and the pole piece so as not to urge the coil It is provided so as to be magnetically held at any of the stable positions of the armature, and when the coil is energized by an appropriate current pulse, the magnetic flux density at the end of the armature adjacent to the axial gap increases and the armature of the armature increases. A bistable magnetic actuator characterized in that the armature moves to another stable position due to a decrease in the magnetic flux density at the other end, and the armature stably stops at that position even after the coil is deenergized. 2. The actuator of claim 1 wherein the permanent magnet is a magnet that is axially magnetized and is mounted at the end of the armature so as to form part of the body of the armature. 3. The actuator according to claim 2, wherein the same magnetic pole of the permanent magnet faces the pole piece. 4. The armature is slidable within a brass tubular liner with a gap therebetween, and the coil is located between the tubular liner and the housing. Actuator. 5. The actuator according to claim 1, wherein the permanent magnet is a magnet magnetized in the axial direction, and is mounted stationary between the armature and the coil. 6. The actuator of claim 5, wherein the same magnetic pole of the permanent magnet faces and engages the pole piece. 7. The actuator according to claim 5, wherein a brass liner in which the actuator is slidable by a gap is provided between the permanent magnet and the actuator. 8. The dimensions of the armature, pole pieces and permanent magnets are such that the extension plane of the end of the armature that engages one pole piece when the armature is in engagement with one pole piece is between the poles of the associated magnet. However, the extension plane at the other end of the armature penetrates between the magnetic poles of the other magnet but far from the other pole piece. The actuator according to claim 5, 6 or 7, wherein the actuator is set. 9. The actuator according to claim 1, wherein the permanent magnet is made of sintered neodymium.